Horizontal Geometry Padding for 360-Degree Video Coding
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Solution Overview
Problem
Current video coding technologies face challenges in effectively handling 360-degree videos, particularly in providing seamless motion compensation and reducing visual artifacts like face seams when projecting and rendering these videos in virtual reality environments, due to the complex geometry and uneven sampling density of spherical projections.
Innovation Solution
The implementation of horizontal geometry padding in video coding devices, which involves determining a reference sample wraparound offset and calculating the correct position of spherical neighbors based on a wraparound enabled indication, allows for accurate prediction and interpolation of samples across the cyclic boundaries of 360-degree video frames, thereby addressing the issues of motion compensation and visual artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional video coding technologies are used for 360-degree videos, then the coding process is simple, but visual artifacts like face seams appear and motion compensation is ineffective
Solution Approach 1:
The patent divides the 360-degree video coding process into distinct segments: identifying wraparound regions, determining reference sample locations with offset adjustments, and applying geometry padding. This segmentation allows each step to be optimized independently, improving rendering quality without overwhelming complexity
Solution Approach 2:
The patent performs preliminary actions by determining reference sample wraparound offsets and identifying correct reference sample locations before actual motion compensation. This preliminary preparation ensures that when motion compensation is performed, the correct reference samples are already positioned, reducing visual artifacts like face seams
2Measurement precision
If standard motion compensation is applied without wraparound handling, then the coding process is straightforward, but motion compensation accuracy deteriorates at cyclic boundaries
Solution Approach 1:
The patent applies local quality by treating boundary regions differently from interior regions. At cyclic boundaries, the system calculates reference sample locations using wraparound offsets to account for the periodic nature of 360-degree video, while interior regions use standard motion compensation. This localized approach improves accuracy where needed without complicating the entire process
Solution Approach 2:
The patent introduces reference sample wraparound offsets as an intermediary element that mediates between standard motion compensation and the cyclic nature of 360-degree video. These offsets act as a bridge, allowing the motion compensation algorithm to correctly access reference samples across cyclic boundaries without requiring complete redesign of the motion compensation process
3Manufacturing precision
If horizontal geometry padding is implemented with wraparound offsets, then visual artifacts are reduced, but the coding complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the reference sample location parameters through wraparound offsets. Instead of changing the fundamental motion compensation algorithm, the system adjusts the location parameters to account for cyclic boundaries. This approach reduces visual artifacts while keeping the implementation complexity manageable by working within the existing parameter framework
Data Source
AI summary
Systems, methods, and instrumentalities are disclosed for performing horizontal geometry padding on a current sample based on receiving a wraparound enabled indication that indicates whether a horizontal wraparound motion compensation is enabled. If the horizontal wraparound motion compensation is enabled based on the wraparound enabled indication, a video coding device may determine a reference sample wraparound offset of a current sample in a picture. The reference sample wraparound offset may indicate a face width of the picture. The video coding device may determine a reference sample location for the current sample based on the reference sample wraparound offset, a picture width of the picture, and a current sample location. The video coding device may predict the current sample based on the reference sample location in a horizontal direction. Repetitive padding or clipping may be used in the vertical direction.